IQO FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. X. 



on the throat and inguinal region, deeper and generally forming a 

 definite ochraceous band across the pectoral region; all the hairs dark 

 slaty at bases; feet buffy white, the forefeet with faint traces of dusky, 

 the hind feet with the proximal fourth more or less ochraceous; tail 

 dusky above, buffy white below. 



Skull rather large and stoutly built, with broad nasals, heavy 

 zygomata, and broad teeth; as compared with that of P. darwini,* it is 

 slightly larger, with broader nasals and ascending branches of pre- 

 maxillae; anterior part of zygomata (infraorbital region) decidedly 

 heavier; mesopterygoid fossa narrower; teeth broader and heavier; 

 incisors especially broad and strong. 



Measurements: Type: Total length 263; head and body 131; tail 

 132; hind foot (c. u.) 28; ear from notch (dry) 22. Skull of type: 

 Greatest length 31.6; basilar length 25.8; zygomatic breadth 17; nasals 

 12.4X4.7; diastema 8; palatine foramina 7. 6 X 2.2; upper toothrow 5.6. 



Remarks: Four specimens of this species were taken by Mr. 

 Anderson in the mountains above the Rio Santa. They show but little 

 variation and seem to represent a species quite distinct from any previ- 

 ously described. Their ochraceous ears and grayish heads suggest 

 possible relationship with the Auliscomys group, but taken as a whole 

 their characters are those of typical Phyllotis. However, it would per- 

 haps not be unfair to look upon the species as a somewhat connecting 

 form between Phyllotis and Auliscomys. Comparison of cranial char- 

 acters has been made with P. darwini mainly because the skull in that 

 species is of approximately the same size; it is obviously not closely 

 related. A species which may have real relationship is P. micropus, 

 which also has dark under parts and a relatively short tail; but this too 

 is well distinguished. 



Auliscomys subg. nov. 



Type, Reiihrodon pictus Thomas. 



Characters: Somewhat intermediate between Euneomys and Phyl- 

 lotis; upper incisors with slight but distinct grooves near the outer edges 

 of their anterior surfaces; molariform teeth slightly more hypsodont 

 than in Phyllotis and with the division of the anterior lobe of the second 

 upper and lower molars persisting throughout a longer period of wear 

 so that these teeth in specimens of average age present three outer angles 

 instead of two; pattern of tooth crowns with angles much less oblique 

 than in Euneomys; maxillary suture in front of infraorbital foramen 



* Specimens from Oroya and Junin, probably representing P. d. posticalis. 



